WIP - chapter 11 save.

Cargo.lock

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Cargo.toml

@@ -22,5 +22,6 @@ members = [
     "chapter-07-damage",
     "chapter-08-ui",
     "chapter-09-items",
-    "chapter-10-ranged"
+    "chapter-10-ranged",
+    "chapter-11-loadsave"
     ]

book/src/SUMMARY.md

@@ -10,3 +10,4 @@
 - [Chapter 8 - User Interface](./chapter_8.md)
 - [Chapter 9 - Items and Inventory](./chapter_9.md)
 - [Chapter 10 - Ranged Scrolls/Targeting](./chapter_10.md)
+- [Chapter 11 - Saving and Loading](./chapter_11.md)

book/src/chapter_11.md

@@ -0,0 +1,223 @@
+# Loading and Saving the Game
+
+---
+
+***About this tutorial***
+
+*This tutorial is free and open source, and all code uses the MIT license - so you are free to do with it as you like. My hope is that you will enjoy the tutorial, and make great games!*
+
+*If you enjoy this and would like me to keep writing, please consider supporting [my Patreon](https://www.patreon.com/blackfuture).*
+
+---
+
+In the last few chapters, we've focused on getting a playable (if not massively fun) game going. You can run around, slay monsters, and make use of various items. That's a great start! Most games let you stop playing, and come back later to continue. Fortunately, Rust (and associated libraries) makes it relatively easy.
+
+# A Main Menu
+
+If you're going to resume a game, you need somewhere from which to do so! A main menu also gives you the option to abandon your last save, possibly view credits, and generally tell the world that your game is here - and written by you. It's an important thing to have, so we'll put one together.
+
+Being in the menu is a *state* - so we'll add it to the ever-expanding `RunState` enum. We want to include menu state inside it, so the definition winds up looking like this:
+
+```rust
+#[derive(PartialEq, Copy, Clone)]
+pub enum RunState { AwaitingInput, 
+    PreRun, 
+    PlayerTurn, 
+    MonsterTurn, 
+    ShowInventory, 
+    ShowDropItem, 
+    ShowTargeting { range : i32, item : Entity},
+    MainMenu { menu_selection : gui::MainMenuSelection }
+}
+```
+
+In `gui.rs`, we add a couple of enum types to handle main menu selections:
+
+```rust
+#[derive(PartialEq, Copy, Clone)]
+pub enum MainMenuSelection { NewGame, LoadGame, Quit }
+
+#[derive(PartialEq, Copy, Clone)]
+pub enum MainMenuResult { NoSelection{ selected : MainMenuSelection }, Selected{ selected: MainMenuSelection } }
+```
+
+Your GUI is probably now telling you that `main.rs` has errors! It's right - we need to handle the new `RunState` option. We'll need to change things around a bit to ensure that we aren't also rendering the GUI and map when in the menu. So we rearrange `tick`:
+
+```rust
+fn tick(&mut self, ctx : &mut Rltk) {
+    let mut newrunstate;
+    {
+        let runstate = self.ecs.fetch::<RunState>();
+        newrunstate = *runstate;
+    }
+
+    ctx.cls();        
+
+    match newrunstate {
+        RunState::MainMenu{..} => {}
+        _ => {
+            draw_map(&self.ecs, ctx);
+
+            {
+                let positions = self.ecs.read_storage::<Position>();
+                let renderables = self.ecs.read_storage::<Renderable>();
+                let map = self.ecs.fetch::<Map>();
+
+                let mut data = (&positions, &renderables).join().collect::<Vec<_>>();
+                data.sort_by(|&a, &b| b.1.render_order.cmp(&a.1.render_order) );
+                for (pos, render) in data.iter() {
+                    let idx = map.xy_idx(pos.x, pos.y);
+                    if map.visible_tiles[idx] { ctx.set(pos.x, pos.y, render.fg, render.bg, render.glyph) }
+                }
+
+                gui::draw_ui(&self.ecs, ctx);
+            } 
+        }
+    }
+    ...
+```
+
+We'll also handle the `MainMenu` state in our large `match` for `RunState`:
+
+```rust
+RunState::MainMenu{ .. } => {
+    let result = gui::main_menu(self, ctx);
+    match result {
+        gui::MainMenuResult::NoSelection{ selected } => newrunstate = RunState::MainMenu{ menu_selection: selected },
+        gui::MainMenuResult::Selected{ selected } => {
+            match selected {
+                gui::MainMenuSelection::NewGame => newrunstate = RunState::PreRun,
+                gui::MainMenuSelection::LoadGame => newrunstate = RunState::PreRun,
+                gui::MainMenuSelection::Quit => { ::std::process::exit(0); }
+            }
+        }
+    }
+}
+```
+
+We're basically updating the state with the new menu selection, and if something has been selected we change the game state. For `Quit`, we simply terminate the process. For now, we'll make loading/starting a game do the same thing: go into the `PreRun` state to setup the game.
+
+The last thing to do is to write the menu itself. In `menu.rs`:
+
+```rust
+pub fn main_menu(gs : &mut State, ctx : &mut Rltk) -> MainMenuResult {
+    let runstate = gs.ecs.fetch::<RunState>();
+
+    ctx.print_color_centered(15, RGB::named(rltk::YELLOW), RGB::named(rltk::BLACK), "Rust Roguelike Tutorial");
+    
+    if let RunState::MainMenu{ menu_selection : selection } = *runstate {
+        if selection == MainMenuSelection::NewGame {
+            ctx.print_color_centered(24, RGB::named(rltk::MAGENTA), RGB::named(rltk::BLACK), "Begin New Game");
+        } else {
+            ctx.print_color_centered(24, RGB::named(rltk::WHITE), RGB::named(rltk::BLACK), "Begin New Game");
+        }
+
+        if selection == MainMenuSelection::LoadGame {
+            ctx.print_color_centered(25, RGB::named(rltk::MAGENTA), RGB::named(rltk::BLACK), "Load Game");
+        } else {
+            ctx.print_color_centered(25, RGB::named(rltk::WHITE), RGB::named(rltk::BLACK), "Load Game");
+        }
+
+        if selection == MainMenuSelection::Quit {
+            ctx.print_color_centered(26, RGB::named(rltk::MAGENTA), RGB::named(rltk::BLACK), "Quit");
+        } else {
+            ctx.print_color_centered(26, RGB::named(rltk::WHITE), RGB::named(rltk::BLACK), "Quit");
+        }
+
+        match ctx.key {
+            None => return MainMenuResult::NoSelection{ selected: selection },
+            Some(key) => {
+                match key {
+                    VirtualKeyCode::Escape => { return MainMenuResult::NoSelection{ selected: MainMenuSelection::Quit } }
+                    VirtualKeyCode::Up => {
+                        let newselection;
+                        match selection {
+                            MainMenuSelection::NewGame => newselection = MainMenuSelection::Quit,
+                            MainMenuSelection::LoadGame => newselection = MainMenuSelection::NewGame,
+                            MainMenuSelection::Quit => newselection = MainMenuSelection::LoadGame
+                        }
+                        return MainMenuResult::NoSelection{ selected: newselection }
+                    }
+                    VirtualKeyCode::Down => {
+                        let newselection;
+                        match selection {
+                            MainMenuSelection::NewGame => newselection = MainMenuSelection::LoadGame,
+                            MainMenuSelection::LoadGame => newselection = MainMenuSelection::Quit,
+                            MainMenuSelection::Quit => newselection = MainMenuSelection::NewGame
+                        }
+                        return MainMenuResult::NoSelection{ selected: newselection }
+                    }
+                    VirtualKeyCode::Return => return MainMenuResult::Selected{ selected : selection },
+                    _ => return MainMenuResult::NoSelection{ selected: selection }
+                }
+            }
+        }
+    }
+
+    MainMenuResult::NoSelection { selected: MainMenuSelection::NewGame }
+}
+```
+
+That's a bit of a mouthful, but it displays menu options and lets you select them with the up/down keys and enter. It's very careful to not modify state itself, to keep things clear.
+
+# Including Serde
+
+`Serde` is pretty much the gold-standard for serialization in Rust. It makes a lot of things easier! So the first step is to include it. In your project's `Cargo.toml` file, we'll expand the `dependencies` section to include it:
+
+```toml
+[dependencies]
+rltk = { git = "https://github.com/thebracket/rltk_rs", features = ["serde"] }
+specs = { version = "0.15.0", features = ["serde"] }
+specs-derive = "0.4.0"
+serde= { version = "1.0.93", features = ["derive"] }
+serde_json = "1.0.39"
+```
+
+It may be worth calling `cargo run` now - it will take a while, downloading the new dependencies (and all of their dependencies) and building them for you. It should keep them around so you don't have to wait this long every time you build.
+
+# Adding a "SaveGame" state
+
+We'll extend `RunState` once more to support game saving:
+
+```rust
+#[derive(PartialEq, Copy, Clone)]
+pub enum RunState { AwaitingInput, 
+    PreRun, 
+    PlayerTurn, 
+    MonsterTurn, 
+    ShowInventory, 
+    ShowDropItem, 
+    ShowTargeting { range : i32, item : Entity},
+    MainMenu { menu_selection : gui::MainMenuSelection },
+    SaveGame
+}
+```
+
+In `tick`, we'll add dummy code for now:
+
+```rust
+RunState::SaveGame => {
+    newrunstate = RunState::MainMenu{ menu_selection : gui::MainMenuSelection::LoadGame };
+}
+```
+
+In `player.rs`, we'll add another keyboard handler - escape:
+
+```rust
+// Save and Quit
+VirtualKeyCode::Escape => return RunState::SaveGame,
+```
+
+If you `cargo run` now, you can start a game and press escape to quit to the menu.
+
+# Actually saving the game
+
+Now that the scaffolding is in place, it's time to actually save something!
+
+**The source code for this chapter may be found [here](https://github.com/thebracket/rustrogueliketutorial/tree/master/chapter-10-ranged)**
+
+---
+
+Copyright (C) 2019, Herbert Wolverson.
+
+---

chapter-11-loadsave/Cargo.toml

@@ -0,0 +1,14 @@
+[package]
+name = "chapter-11-loadsave"
+version = "0.1.0"
+authors = ["Herbert Wolverson <herberticus@gmail.com>"]
+edition = "2018"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+rltk = { git = "https://github.com/thebracket/rltk_rs", features = ["serde"] }
+specs = { version = "0.15.0", features = ["serde"] }
+specs-derive = "0.4.0"
+serde= { version = "1.0", features = ["derive"] }
+serde_json = "1.0"

chapter-11-loadsave/src/components.rs

@@ -0,0 +1,111 @@
+extern crate specs;
+use specs::prelude::*;
+extern crate specs_derive;
+extern crate rltk;
+use rltk::{RGB};
+
+#[derive(Component)]
+pub struct Position {
+    pub x: i32,
+    pub y: i32,
+}
+
+#[derive(Component)]
+pub struct Renderable {
+    pub glyph: u8,
+    pub fg: RGB,
+    pub bg: RGB,
+    pub render_order : i32
+}
+ 
+#[derive(Component, Debug)]
+pub struct Player {}
+
+#[derive(Component)]
+pub struct Viewshed {
+    pub visible_tiles : Vec<rltk::Point>,
+    pub range : i32,
+    pub dirty : bool
+}
+
+#[derive(Component, Debug)]
+pub struct Monster {}
+
+#[derive(Component, Debug)]
+pub struct Name {
+    pub name : String
+}
+
+#[derive(Component, Debug)]
+pub struct BlocksTile {}
+
+#[derive(Component, Debug)]
+pub struct CombatStats {
+    pub max_hp : i32,
+    pub hp : i32,
+    pub defense : i32,
+    pub power : i32
+}
+
+#[derive(Component, Debug)]
+pub struct WantsToMelee {
+    pub target : Entity
+}
+
+#[derive(Component, Debug)]
+pub struct SufferDamage {
+    pub amount : i32
+}
+
+#[derive(Component, Debug)]
+pub struct Item {}
+
+#[derive(Component, Debug)]
+pub struct Consumable {}
+
+#[derive(Component, Debug)]
+pub struct Ranged {
+    pub range : i32
+}
+
+#[derive(Component, Debug)]
+pub struct InflictsDamage {
+    pub damage : i32
+}
+
+#[derive(Component, Debug)]
+pub struct AreaOfEffect {
+    pub radius : i32
+}
+
+#[derive(Component, Debug)]
+pub struct Confusion {
+    pub turns : i32
+}
+
+#[derive(Component, Debug)]
+pub struct ProvidesHealing {
+    pub heal_amount : i32
+}
+
+#[derive(Component, Debug)]
+pub struct InBackpack {
+    pub owner : Entity
+}
+
+#[derive(Component, Debug)]
+pub struct WantsToPickupItem {
+    pub collected_by : Entity,
+    pub item : Entity
+}
+
+#[derive(Component, Debug)]
+pub struct WantsToUseItem {
+    pub item : Entity,
+    pub target : Option<rltk::Point>
+}
+
+#[derive(Component, Debug)]
+pub struct WantsToDropItem {
+    pub item : Entity
+}

chapter-11-loadsave/src/damage_system.rs

@@ -0,0 +1,51 @@
+extern crate specs;
+use specs::prelude::*;
+use super::{CombatStats, SufferDamage, Player, Name, gamelog::GameLog};
+
+pub struct DamageSystem {}
+
+impl<'a> System<'a> for DamageSystem {
+    type SystemData = ( WriteStorage<'a, CombatStats>,
+                        WriteStorage<'a, SufferDamage> );
+
+    fn run(&mut self, data : Self::SystemData) {
+        let (mut stats, mut damage) = data;
+
+        for (mut stats, damage) in (&mut stats, &damage).join() {
+            stats.hp -= damage.amount;
+        }
+
+        damage.clear();
+    }
+}
+
+pub fn delete_the_dead(ecs : &mut World) {
+    let mut dead : Vec<Entity> = Vec::new();
+    // Using a scope to make the borrow checker happy
+    {
+        let combat_stats = ecs.read_storage::<CombatStats>();
+        let players = ecs.read_storage::<Player>();
+        let names = ecs.read_storage::<Name>();
+        let entities = ecs.entities();
+        let mut log = ecs.write_resource::<GameLog>();
+        for (entity, stats) in (&entities, &combat_stats).join() {
+            if stats.hp < 1 { 
+                let player = players.get(entity);
+                match player {
+                    None => {
+                        let victim_name = names.get(entity);
+                        if let Some(victim_name) = victim_name {
+                            log.entries.insert(0, format!("{} is dead", &victim_name.name));
+                        }
+                        dead.push(entity)
+                    }
+                    Some(_) => println!("You are dead")
+                }
+            }
+        }
+    }
+
+    for victim in dead {
+        ecs.delete_entity(victim).expect("Unable to delete");
+    }    
+}

chapter-11-loadsave/src/gamelog.rs

@@ -0,0 +1,3 @@
+pub struct GameLog {
+    pub entries : Vec<String>
+}

chapter-11-loadsave/src/gui.rs

@@ -0,0 +1,278 @@
+extern crate rltk;
+use rltk::{ RGB, Rltk, Console, Point, VirtualKeyCode };
+extern crate specs;
+use specs::prelude::*;
+use super::{CombatStats, Player, gamelog::GameLog, Map, Name, Position, State, InBackpack, 
+    Viewshed, RunState};
+
+pub fn draw_ui(ecs: &World, ctx : &mut Rltk) {
+    ctx.draw_box(0, 43, 79, 6, RGB::named(rltk::WHITE), RGB::named(rltk::BLACK));
+
+    let combat_stats = ecs.read_storage::<CombatStats>();
+    let players = ecs.read_storage::<Player>();
+    for (_player, stats) in (&players, &combat_stats).join() {
+        let health = format!(" HP: {} / {} ", stats.hp, stats.max_hp);
+        ctx.print_color(12, 43, RGB::named(rltk::YELLOW), RGB::named(rltk::BLACK), &health);
+
+        ctx.draw_bar_horizontal(28, 43, 51, stats.hp, stats.max_hp, RGB::named(rltk::RED), RGB::named(rltk::BLACK));
+    }
+
+    let log = ecs.fetch::<GameLog>();
+    let mut y = 44;
+    for s in log.entries.iter() {
+        if y < 49 { ctx.print(2, y, &s.to_string()); }
+        y += 1;
+    }
+
+    // Draw mouse cursor
+    let mouse_pos = ctx.mouse_pos();
+    ctx.set_bg(mouse_pos.0, mouse_pos.1, RGB::named(rltk::MAGENTA));
+    draw_tooltips(ecs, ctx);
+}
+
+fn draw_tooltips(ecs: &World, ctx : &mut Rltk) {
+    let map = ecs.fetch::<Map>();
+    let names = ecs.read_storage::<Name>();
+    let positions = ecs.read_storage::<Position>();
+
+    let mouse_pos = ctx.mouse_pos();
+    if mouse_pos.0 >= map.width || mouse_pos.1 >= map.height { return; }
+    let mut tooltip : Vec<String> = Vec::new();
+    for (name, position) in (&names, &positions).join() {
+        if position.x == mouse_pos.0 && position.y == mouse_pos.1 {
+            tooltip.push(name.name.to_string());
+        }
+    }
+
+    if !tooltip.is_empty() {
+        let mut width :i32 = 0;
+        for s in tooltip.iter() {
+            if width < s.len() as i32 { width = s.len() as i32; }
+        }
+        width += 3;
+
+        if mouse_pos.0 > 40 {
+            let arrow_pos = Point::new(mouse_pos.0 - 2, mouse_pos.1);
+            let left_x = mouse_pos.0 - width;
+            let mut y = mouse_pos.1;
+            for s in tooltip.iter() {
+                ctx.print_color(left_x, y, RGB::named(rltk::WHITE), RGB::named(rltk::GREY), &s.to_string());
+                let padding = (width - s.len() as i32)-1;
+                for i in 0..padding {
+                    ctx.print_color(arrow_pos.x - i, y, RGB::named(rltk::WHITE), RGB::named(rltk::GREY), &" ".to_string());
+                }
+                y += 1;
+            }
+            ctx.print_color(arrow_pos.x, arrow_pos.y, RGB::named(rltk::WHITE), RGB::named(rltk::GREY), &"->".to_string());
+        } else {
+            let arrow_pos = Point::new(mouse_pos.0 + 1, mouse_pos.1);
+            let left_x = mouse_pos.0 +3;
+            let mut y = mouse_pos.1;
+            for s in tooltip.iter() {
+                ctx.print_color(left_x, y, RGB::named(rltk::WHITE), RGB::named(rltk::GREY), &s.to_string());
+                let padding = (width - s.len() as i32)-1;
+                for i in 0..padding {
+                    ctx.print_color(left_x + s.len() as i32 + i, y, RGB::named(rltk::WHITE), RGB::named(rltk::GREY), &" ".to_string());
+                }
+                y += 1;
+            }
+            ctx.print_color(arrow_pos.x, arrow_pos.y, RGB::named(rltk::WHITE), RGB::named(rltk::GREY), &"<-".to_string());
+        }
+    }
+}
+
+#[derive(PartialEq, Copy, Clone)]
+pub enum ItemMenuResult { Cancel, NoResponse, Selected }
+
+pub fn show_inventory(gs : &mut State, ctx : &mut Rltk) -> (ItemMenuResult, Option<Entity>) {
+    let player_entity = gs.ecs.fetch::<Entity>();
+    let names = gs.ecs.read_storage::<Name>();
+    let backpack = gs.ecs.read_storage::<InBackpack>();
+    let entities = gs.ecs.entities();
+
+    let inventory = (&backpack, &names).join().filter(|item| item.0.owner == *player_entity );
+    let count = inventory.count();
+
+    let mut y = (25 - (count / 2)) as i32;
+    ctx.draw_box(15, y-2, 31, (count+3) as i32, RGB::named(rltk::WHITE), RGB::named(rltk::BLACK));
+    ctx.print_color(18, y-2, RGB::named(rltk::YELLOW), RGB::named(rltk::BLACK), "Inventory");
+    ctx.print_color(18, y+count as i32+1, RGB::named(rltk::YELLOW), RGB::named(rltk::BLACK), "ESCAPE to cancel");
+
+    let mut equippable : Vec<Entity> = Vec::new();
+    let mut j = 0;
+    for (entity, _pack, name) in (&entities, &backpack, &names).join().filter(|item| item.1.owner == *player_entity ) {
+        ctx.set(17, y, RGB::named(rltk::WHITE), RGB::named(rltk::BLACK), rltk::to_cp437('('));
+        ctx.set(18, y, RGB::named(rltk::YELLOW), RGB::named(rltk::BLACK), 97+j as u8);
+        ctx.set(19, y, RGB::named(rltk::WHITE), RGB::named(rltk::BLACK), rltk::to_cp437(')'));
+
+        ctx.print(21, y, &name.name.to_string());
+        equippable.push(entity);
+        y += 1;
+        j += 1;
+    }
+
+    match ctx.key {
+        None => (ItemMenuResult::NoResponse, None),
+        Some(key) => {
+            match key {
+                VirtualKeyCode::Escape => { (ItemMenuResult::Cancel, None) }
+                _ => { 
+                    let selection = rltk::letter_to_option(key);
+                    if selection > -1 && selection < count as i32 {
+                        return (ItemMenuResult::Selected, Some(equippable[selection as usize]));
+                    }  
+                    (ItemMenuResult::NoResponse, None)
+                }
+            }
+        }
+    }
+}
+
+pub fn drop_item_menu(gs : &mut State, ctx : &mut Rltk) -> (ItemMenuResult, Option<Entity>) {
+    let player_entity = gs.ecs.fetch::<Entity>();
+    let names = gs.ecs.read_storage::<Name>();
+    let backpack = gs.ecs.read_storage::<InBackpack>();
+    let entities = gs.ecs.entities();
+
+    let inventory = (&backpack, &names).join().filter(|item| item.0.owner == *player_entity );
+    let count = inventory.count();
+
+    let mut y = (25 - (count / 2)) as i32;
+    ctx.draw_box(15, y-2, 31, (count+3) as i32, RGB::named(rltk::WHITE), RGB::named(rltk::BLACK));
+    ctx.print_color(18, y-2, RGB::named(rltk::YELLOW), RGB::named(rltk::BLACK), "Drop Which Item?");
+    ctx.print_color(18, y+count as i32+1, RGB::named(rltk::YELLOW), RGB::named(rltk::BLACK), "ESCAPE to cancel");
+
+    let mut equippable : Vec<Entity> = Vec::new();
+    let mut j = 0;
+    for (entity, _pack, name) in (&entities, &backpack, &names).join().filter(|item| item.1.owner == *player_entity ) {
+        ctx.set(17, y, RGB::named(rltk::WHITE), RGB::named(rltk::BLACK), rltk::to_cp437('('));
+        ctx.set(18, y, RGB::named(rltk::YELLOW), RGB::named(rltk::BLACK), 97+j as u8);
+        ctx.set(19, y, RGB::named(rltk::WHITE), RGB::named(rltk::BLACK), rltk::to_cp437(')'));
+
+        ctx.print(21, y, &name.name.to_string());
+        equippable.push(entity);
+        y += 1;
+        j += 1;
+    }
+
+    match ctx.key {
+        None => (ItemMenuResult::NoResponse, None),
+        Some(key) => {
+            match key {
+                VirtualKeyCode::Escape => { (ItemMenuResult::Cancel, None) }
+                _ => { 
+                    let selection = rltk::letter_to_option(key);
+                    if selection > -1 && selection < count as i32 {
+                        return (ItemMenuResult::Selected, Some(equippable[selection as usize]));
+                    }  
+                    (ItemMenuResult::NoResponse, None)
+                }
+            }
+        }
+    }
+}
+
+pub fn ranged_target(gs : &mut State, ctx : &mut Rltk, range : i32) -> (ItemMenuResult, Option<Point>) {
+    let player_entity = gs.ecs.fetch::<Entity>();
+    let player_pos = gs.ecs.fetch::<Point>();
+    let viewsheds = gs.ecs.read_storage::<Viewshed>();
+
+    ctx.print_color(5, 0, RGB::named(rltk::YELLOW), RGB::named(rltk::BLACK), "Select Target:");
+
+    // Highlight available target cells
+    let mut available_cells = Vec::new();
+    let visible = viewsheds.get(*player_entity);
+    if let Some(visible) = visible {
+        // We have a viewshed
+        for idx in visible.visible_tiles.iter() {
+            let distance = rltk::DistanceAlg::Pythagoras.distance2d(*player_pos, *idx);
+            if distance <= range as f32 {
+                ctx.set_bg(idx.x, idx.y, RGB::named(rltk::BLUE));
+                available_cells.push(idx);
+            }
+        }
+    } else {
+        return (ItemMenuResult::Cancel, None);
+    }
+
+    // Draw mouse cursor
+    let mouse_pos = ctx.mouse_pos();
+    let mut valid_target = false;
+    for idx in available_cells.iter() { if idx.x == mouse_pos.0 && idx.y == mouse_pos.1 { valid_target = true; } }
+    if valid_target {
+        ctx.set_bg(mouse_pos.0, mouse_pos.1, RGB::named(rltk::CYAN));
+        if ctx.left_click {
+            return (ItemMenuResult::Selected, Some(Point::new(mouse_pos.0, mouse_pos.1)));
+        }
+    } else {
+        ctx.set_bg(mouse_pos.0, mouse_pos.1, RGB::named(rltk::RED));
+        if ctx.left_click {
+            return (ItemMenuResult::Cancel, None);
+        }
+    }
+
+    (ItemMenuResult::NoResponse, None)
+}
+
+#[derive(PartialEq, Copy, Clone)]
+pub enum MainMenuSelection { NewGame, LoadGame, Quit }
+
+#[derive(PartialEq, Copy, Clone)]
+pub enum MainMenuResult { NoSelection{ selected : MainMenuSelection }, Selected{ selected: MainMenuSelection } }
+
+pub fn main_menu(gs : &mut State, ctx : &mut Rltk) -> MainMenuResult {
+    let runstate = gs.ecs.fetch::<RunState>();
+
+    ctx.print_color_centered(15, RGB::named(rltk::YELLOW), RGB::named(rltk::BLACK), "Rust Roguelike Tutorial");
+    
+    if let RunState::MainMenu{ menu_selection : selection } = *runstate {
+        if selection == MainMenuSelection::NewGame {
+            ctx.print_color_centered(24, RGB::named(rltk::MAGENTA), RGB::named(rltk::BLACK), "Begin New Game");
+        } else {
+            ctx.print_color_centered(24, RGB::named(rltk::WHITE), RGB::named(rltk::BLACK), "Begin New Game");
+        }
+
+        if selection == MainMenuSelection::LoadGame {
+            ctx.print_color_centered(25, RGB::named(rltk::MAGENTA), RGB::named(rltk::BLACK), "Load Game");
+        } else {
+            ctx.print_color_centered(25, RGB::named(rltk::WHITE), RGB::named(rltk::BLACK), "Load Game");
+        }
+
+        if selection == MainMenuSelection::Quit {
+            ctx.print_color_centered(26, RGB::named(rltk::MAGENTA), RGB::named(rltk::BLACK), "Quit");
+        } else {
+            ctx.print_color_centered(26, RGB::named(rltk::WHITE), RGB::named(rltk::BLACK), "Quit");
+        }
+
+        match ctx.key {
+            None => return MainMenuResult::NoSelection{ selected: selection },
+            Some(key) => {
+                match key {
+                    VirtualKeyCode::Escape => { return MainMenuResult::NoSelection{ selected: MainMenuSelection::Quit } }
+                    VirtualKeyCode::Up => {
+                        let newselection;
+                        match selection {
+                            MainMenuSelection::NewGame => newselection = MainMenuSelection::Quit,
+                            MainMenuSelection::LoadGame => newselection = MainMenuSelection::NewGame,
+                            MainMenuSelection::Quit => newselection = MainMenuSelection::LoadGame
+                        }
+                        return MainMenuResult::NoSelection{ selected: newselection }
+                    }
+                    VirtualKeyCode::Down => {
+                        let newselection;
+                        match selection {
+                            MainMenuSelection::NewGame => newselection = MainMenuSelection::LoadGame,
+                            MainMenuSelection::LoadGame => newselection = MainMenuSelection::Quit,
+                            MainMenuSelection::Quit => newselection = MainMenuSelection::NewGame
+                        }
+                        return MainMenuResult::NoSelection{ selected: newselection }
+                    }
+                    VirtualKeyCode::Return => return MainMenuResult::Selected{ selected : selection },
+                    _ => return MainMenuResult::NoSelection{ selected: selection }
+                }
+            }
+        }
+    }
+
+    MainMenuResult::NoSelection { selected: MainMenuSelection::NewGame }
+}

chapter-11-loadsave/src/inventory_system.rs

@@ -0,0 +1,200 @@
+extern crate specs;
+use specs::prelude::*;
+use super::{WantsToPickupItem, Name, InBackpack, Position, gamelog::GameLog, WantsToUseItem, 
+    Consumable, ProvidesHealing, CombatStats, WantsToDropItem, InflictsDamage, Map, SufferDamage,
+    AreaOfEffect, Confusion};
+
+pub struct ItemCollectionSystem {}
+
+impl<'a> System<'a> for ItemCollectionSystem {
+    #[allow(clippy::type_complexity)]
+    type SystemData = ( ReadExpect<'a, Entity>,
+                        WriteExpect<'a, GameLog>,
+                        WriteStorage<'a, WantsToPickupItem>,
+                        WriteStorage<'a, Position>,
+                        ReadStorage<'a, Name>,
+                        WriteStorage<'a, InBackpack>
+                      );
+
+    fn run(&mut self, data : Self::SystemData) {
+        let (player_entity, mut gamelog, mut wants_pickup, mut positions, names, mut backpack) = data;
+
+        for pickup in wants_pickup.join() {
+            positions.remove(pickup.item);
+            backpack.insert(pickup.item, InBackpack{ owner: pickup.collected_by }).expect("Unable to insert backpack entry");
+
+            if pickup.collected_by == *player_entity {
+                gamelog.entries.insert(0, format!("You pick up the {}.", names.get(pickup.item).unwrap().name));
+            }
+        }
+
+        wants_pickup.clear();
+    }
+}
+
+pub struct ItemUseSystem {}
+
+impl<'a> System<'a> for ItemUseSystem {
+    #[allow(clippy::type_complexity)]
+    type SystemData = ( ReadExpect<'a, Entity>,
+                        WriteExpect<'a, GameLog>,
+                        ReadExpect<'a, Map>,
+                        Entities<'a>,
+                        WriteStorage<'a, WantsToUseItem>,
+                        ReadStorage<'a, Name>,
+                        ReadStorage<'a, Consumable>,
+                        ReadStorage<'a, ProvidesHealing>,
+                        ReadStorage<'a, InflictsDamage>,
+                        WriteStorage<'a, CombatStats>,
+                        WriteStorage<'a, SufferDamage>,
+                        ReadStorage<'a, AreaOfEffect>,
+                        WriteStorage<'a, Confusion>
+                      );
+
+    fn run(&mut self, data : Self::SystemData) {
+        let (player_entity, mut gamelog, map, entities, mut wants_use, names, 
+            consumables, healing, inflict_damage, mut combat_stats, mut suffer_damage, 
+            aoe, mut confused) = data;
+
+        for (entity, useitem) in (&entities, &wants_use).join() {
+            let mut used_item = true;
+
+            // Targeting
+            let mut targets : Vec<Entity> = Vec::new();
+            match useitem.target {
+                None => { targets.push( *player_entity ); }
+                Some(target) => {
+                    let area_effect = aoe.get(useitem.item);
+                    match area_effect {
+                        None => {
+                            // Single target in tile
+                            let idx = map.xy_idx(target.x, target.y);
+                            for mob in map.tile_content[idx].iter() {
+                                targets.push(*mob);
+                            }
+                        }
+                        Some(area_effect) => {
+                            // AoE
+                            let blast_tiles = rltk::field_of_view(target, area_effect.radius, &*map);
+                            for tile_idx in blast_tiles.iter() {
+                                let idx = map.xy_idx(tile_idx.x, tile_idx.y);
+                                for mob in map.tile_content[idx].iter() {
+                                    targets.push(*mob);
+                                }
+                            }
+                        }
+                    }
+                }
+            }
+
+            // If it heals, apply the healing
+            let item_heals = healing.get(useitem.item);
+            match item_heals {
+                None => {}
+                Some(healer) => {
+                    used_item = false;
+                    for target in targets.iter() {
+                        let stats = combat_stats.get_mut(*target);
+                        if let Some(stats) = stats {
+                            stats.hp = i32::max(stats.max_hp, stats.hp + healer.heal_amount);
+                            if entity == *player_entity {
+                                gamelog.entries.insert(0, format!("You use the {}, healing {} hp.", names.get(useitem.item).unwrap().name, healer.heal_amount));
+                            }
+                            used_item = true;
+                        }                        
+                    }
+                }
+            }
+
+            // If it inflicts damage, apply it to the target cell
+            let item_damages = inflict_damage.get(useitem.item);
+            match item_damages {
+                None => {}
+                Some(damage) => {
+                    used_item = false;
+                    for mob in targets.iter() {
+                        suffer_damage.insert(*mob, SufferDamage{ amount : damage.damage }).expect("Unable to insert");
+                        if entity == *player_entity {
+                            let mob_name = names.get(*mob).unwrap();
+                            let item_name = names.get(useitem.item).unwrap();
+                            gamelog.entries.insert(0, format!("You use {} on {}, inflicting {} hp.", item_name.name, mob_name.name, damage.damage));
+                        }
+
+                        used_item = true;
+                    }
+                }
+            }
+
+            // Can it pass along confusion? Note the use of scopes to escape from the borrow checker!
+            let mut add_confusion = Vec::new();
+            {
+                let causes_confusion = confused.get(useitem.item);
+                match causes_confusion {
+                    None => {}
+                    Some(confusion) => {
+                        used_item = false;
+                        for mob in targets.iter() {
+                            add_confusion.push((*mob, confusion.turns ));
+                            if entity == *player_entity {
+                                let mob_name = names.get(*mob).unwrap();
+                                let item_name = names.get(useitem.item).unwrap();
+                                gamelog.entries.insert(0, format!("You use {} on {}, confusing them.", item_name.name, mob_name.name));
+                            }
+                        }
+                    }
+                }
+            }
+            for mob in add_confusion.iter() {
+                confused.insert(mob.0, Confusion{ turns: mob.1 }).expect("Unable to insert status");
+            }
+
+            // If its a consumable, we delete it on use
+            if used_item {
+                let consumable = consumables.get(useitem.item);
+                match consumable {
+                    None => {}
+                    Some(_) => {
+                        entities.delete(useitem.item).expect("Delete failed");
+                    }
+                }
+            }
+        }
+
+        wants_use.clear();
+    }
+}
+
+pub struct ItemDropSystem {}
+
+impl<'a> System<'a> for ItemDropSystem {
+    #[allow(clippy::type_complexity)]
+    type SystemData = ( ReadExpect<'a, Entity>,
+                        WriteExpect<'a, GameLog>,
+                        Entities<'a>,
+                        WriteStorage<'a, WantsToDropItem>,
+                        ReadStorage<'a, Name>,
+                        WriteStorage<'a, Position>,
+                        WriteStorage<'a, InBackpack>
+                      );
+
+    fn run(&mut self, data : Self::SystemData) {
+        let (player_entity, mut gamelog, entities, mut wants_drop, names, mut positions, mut backpack) = data;
+
+        for (entity, to_drop) in (&entities, &wants_drop).join() {
+            let mut dropper_pos : Position = Position{x:0, y:0};
+            {
+                let dropped_pos = positions.get(entity).unwrap();
+                dropper_pos.x = dropped_pos.x;
+                dropper_pos.y = dropped_pos.y;
+            }
+            positions.insert(to_drop.item, Position{ x : dropper_pos.x, y : dropper_pos.y }).expect("Unable to insert position");
+            backpack.remove(to_drop.item);
+
+            if entity == *player_entity {
+                gamelog.entries.insert(0, format!("You drop up the {}.", names.get(to_drop.item).unwrap().name));
+            }
+        }
+
+        wants_drop.clear();
+    }
+}

chapter-11-loadsave/src/main.rs

@@ -0,0 +1,234 @@
+extern crate serde;
+use serde::{Serialize, Deserialize};
+extern crate rltk;
+use rltk::{Console, GameState, Rltk, Point};
+extern crate specs;
+use specs::prelude::*;
+#[macro_use]
+extern crate specs_derive;
+mod components;
+pub use components::*;
+mod map;
+pub use map::*;
+mod player;
+use player::*;
+mod rect;
+pub use rect::Rect;
+mod visibility_system;
+use visibility_system::VisibilitySystem;
+mod monster_ai_system;
+use monster_ai_system::MonsterAI;
+mod map_indexing_system;
+use map_indexing_system::MapIndexingSystem;
+mod melee_combat_system;
+use melee_combat_system::MeleeCombatSystem;
+mod damage_system;
+use damage_system::DamageSystem;
+mod gui;
+mod gamelog;
+mod spawner;
+mod inventory_system;
+use inventory_system::{ ItemCollectionSystem, ItemUseSystem, ItemDropSystem };
+use std::fs;
+use std::fs::File;
+use std::io::Write;
+use std::path::Path;
+
+#[derive(PartialEq, Copy, Clone)]
+pub enum RunState { AwaitingInput, 
+    PreRun, 
+    PlayerTurn, 
+    MonsterTurn, 
+    ShowInventory, 
+    ShowDropItem, 
+    ShowTargeting { range : i32, item : Entity},
+    MainMenu { menu_selection : gui::MainMenuSelection },
+    SaveGame
+}
+
+pub struct State {
+    pub ecs: World,
+    pub systems: Dispatcher<'static, 'static>
+}
+
+impl GameState for State {
+    fn tick(&mut self, ctx : &mut Rltk) {
+        let mut newrunstate;
+        {
+            let runstate = self.ecs.fetch::<RunState>();
+            newrunstate = *runstate;
+        }
+
+        ctx.cls();        
+
+        match newrunstate {
+            RunState::MainMenu{..} => {}
+            _ => {
+                draw_map(&self.ecs, ctx);
+
+                {
+                    let positions = self.ecs.read_storage::<Position>();
+                    let renderables = self.ecs.read_storage::<Renderable>();
+                    let map = self.ecs.fetch::<Map>();
+
+                    let mut data = (&positions, &renderables).join().collect::<Vec<_>>();
+                    data.sort_by(|&a, &b| b.1.render_order.cmp(&a.1.render_order) );
+                    for (pos, render) in data.iter() {
+                        let idx = map.xy_idx(pos.x, pos.y);
+                        if map.visible_tiles[idx] { ctx.set(pos.x, pos.y, render.fg, render.bg, render.glyph) }
+                    }
+
+                    gui::draw_ui(&self.ecs, ctx);
+                } 
+            }
+        }
+        
+        match newrunstate {
+            RunState::PreRun => {
+                self.systems.dispatch(&self.ecs);
+                self.ecs.maintain();
+                newrunstate = RunState::AwaitingInput;
+            }
+            RunState::AwaitingInput => {
+                newrunstate = player_input(self, ctx);
+            }
+            RunState::PlayerTurn => {
+                self.systems.dispatch(&self.ecs);
+                self.ecs.maintain();
+                newrunstate = RunState::MonsterTurn;
+            }
+            RunState::MonsterTurn => {
+                self.systems.dispatch(&self.ecs);
+                self.ecs.maintain();
+                newrunstate = RunState::AwaitingInput;
+            }
+            RunState::ShowInventory => {
+                let result = gui::show_inventory(self, ctx);
+                match result.0 {
+                    gui::ItemMenuResult::Cancel => newrunstate = RunState::AwaitingInput,
+                    gui::ItemMenuResult::NoResponse => {}
+                    gui::ItemMenuResult::Selected => {
+                        let item_entity = result.1.unwrap();
+                        let is_ranged = self.ecs.read_storage::<Ranged>();
+                        let is_item_ranged = is_ranged.get(item_entity);
+                        if let Some(is_item_ranged) = is_item_ranged {
+                            newrunstate = RunState::ShowTargeting{ range: is_item_ranged.range, item: item_entity };
+                        } else {
+                            let mut intent = self.ecs.write_storage::<WantsToUseItem>();
+                            intent.insert(*self.ecs.fetch::<Entity>(), WantsToUseItem{ item: item_entity, target: None }).expect("Unable to insert intent");
+                            newrunstate = RunState::PlayerTurn;
+                        }
+                    }
+                }
+            }
+            RunState::ShowDropItem => {
+                let result = gui::drop_item_menu(self, ctx);
+                match result.0 {
+                    gui::ItemMenuResult::Cancel => newrunstate = RunState::AwaitingInput,
+                    gui::ItemMenuResult::NoResponse => {}
+                    gui::ItemMenuResult::Selected => {
+                        let item_entity = result.1.unwrap();
+                        let mut intent = self.ecs.write_storage::<WantsToDropItem>();
+                        intent.insert(*self.ecs.fetch::<Entity>(), WantsToDropItem{ item: item_entity }).expect("Unable to insert intent");
+                        newrunstate = RunState::PlayerTurn;
+                    }
+                }
+            }
+            RunState::ShowTargeting{range, item} => {
+                let result = gui::ranged_target(self, ctx, range);
+                match result.0 {
+                    gui::ItemMenuResult::Cancel => newrunstate = RunState::AwaitingInput,
+                    gui::ItemMenuResult::NoResponse => {}
+                    gui::ItemMenuResult::Selected => {
+                        let mut intent = self.ecs.write_storage::<WantsToUseItem>();
+                        intent.insert(*self.ecs.fetch::<Entity>(), WantsToUseItem{ item, target: result.1 }).expect("Unable to insert intent");
+                        newrunstate = RunState::PlayerTurn;
+                    }
+                }
+            }
+            RunState::MainMenu{ .. } => {
+                let result = gui::main_menu(self, ctx);
+                match result {
+                    gui::MainMenuResult::NoSelection{ selected } => newrunstate = RunState::MainMenu{ menu_selection: selected },
+                    gui::MainMenuResult::Selected{ selected } => {
+                        match selected {
+                            gui::MainMenuSelection::NewGame => newrunstate = RunState::PreRun,
+                            gui::MainMenuSelection::LoadGame => newrunstate = RunState::PreRun,
+                            gui::MainMenuSelection::Quit => { ::std::process::exit(0); }
+                        }
+                    }
+                }
+            }
+            RunState::SaveGame => {
+                //let data = serde_json::to_string(&*self.ecs.fetch::<Map>()).unwrap();
+                //let mut f = File::create("./savegame.json").expect("Unable to create file");
+                //f.write_all(data.as_bytes()).expect("Unable to write data");
+
+                newrunstate = RunState::MainMenu{ menu_selection : gui::MainMenuSelection::LoadGame };
+            }
+        }
+
+        {
+            let mut runwriter = self.ecs.write_resource::<RunState>();
+            *runwriter = newrunstate;
+        }
+        damage_system::delete_the_dead(&mut self.ecs);
+    }
+}
+
+fn main() {
+    let mut context = Rltk::init_simple8x8(80, 50, "Hello Rust World", "../resources");
+    context.with_post_scanlines(true);
+    let mut gs = State {
+        ecs: World::new(),
+        systems : DispatcherBuilder::new()
+            .with(MapIndexingSystem{}, "map_indexing_system", &[])
+            .with(VisibilitySystem{}, "visibility_system", &[])
+            .with(MonsterAI{}, "monster_ai", &["visibility_system", "map_indexing_system"])
+            .with(MeleeCombatSystem{}, "melee_combat", &["monster_ai"])
+            .with(DamageSystem{}, "damage", &["melee_combat"])
+            .with(ItemCollectionSystem{}, "pickup", &["melee_combat"])
+            .with(ItemUseSystem{}, "potions", &["melee_combat"])
+            .with(ItemDropSystem{}, "drop_items", &["melee_combat"])
+            .build(),
+    };
+    gs.ecs.register::<Position>();
+    gs.ecs.register::<Renderable>();
+    gs.ecs.register::<Player>();
+    gs.ecs.register::<Viewshed>();
+    gs.ecs.register::<Monster>();
+    gs.ecs.register::<Name>();
+    gs.ecs.register::<BlocksTile>();
+    gs.ecs.register::<CombatStats>();
+    gs.ecs.register::<WantsToMelee>();
+    gs.ecs.register::<SufferDamage>();
+    gs.ecs.register::<Item>();
+    gs.ecs.register::<ProvidesHealing>();
+    gs.ecs.register::<InflictsDamage>();
+    gs.ecs.register::<AreaOfEffect>();
+    gs.ecs.register::<Consumable>();
+    gs.ecs.register::<Ranged>();
+    gs.ecs.register::<InBackpack>();
+    gs.ecs.register::<WantsToPickupItem>();
+    gs.ecs.register::<WantsToUseItem>();
+    gs.ecs.register::<WantsToDropItem>();
+    gs.ecs.register::<Confusion>();
+
+    let map : Map = Map::new_map_rooms_and_corridors();
+    let (player_x, player_y) = map.rooms[0].center();
+
+    let player_entity = spawner::player(&mut gs.ecs, player_x, player_y);
+
+    gs.ecs.insert(rltk::RandomNumberGenerator::new());
+    for room in map.rooms.iter().skip(1) {
+        spawner::spawn_room(&mut gs.ecs, room);
+    }
+
+    gs.ecs.insert(map);
+    gs.ecs.insert(Point::new(player_x, player_y));
+    gs.ecs.insert(player_entity);
+    gs.ecs.insert(RunState::MainMenu{ menu_selection: gui::MainMenuSelection::NewGame });
+    gs.ecs.insert(gamelog::GameLog{ entries : vec!["Welcome to Rusty Roguelike".to_string()] });
+
+    rltk::main_loop(context, gs);
+}

chapter-11-loadsave/src/map.rs

@@ -0,0 +1,206 @@
+extern crate rltk;
+use rltk::{ RGB, Rltk, Console, RandomNumberGenerator, BaseMap, Algorithm2D, Point };
+use super::{Rect};
+use std::cmp::{max, min};
+extern crate specs;
+use specs::prelude::*;
+
+pub const MAPWIDTH : usize = 80;
+pub const MAPHEIGHT : usize = 43;
+pub const MAPCOUNT : usize = MAPHEIGHT * MAPWIDTH;
+
+#[derive(PartialEq, Copy, Clone)]
+pub enum TileType {
+    Wall, Floor
+}
+
+#[derive(Default)]
+pub struct Map {
+    pub tiles : Vec<TileType>,
+    pub rooms : Vec<Rect>,
+    pub width : i32,
+    pub height : i32,
+    pub revealed_tiles : Vec<bool>,
+    pub visible_tiles : Vec<bool>,
+    pub blocked : Vec<bool>,
+    pub tile_content : Vec<Vec<Entity>>
+}
+
+impl Map {
+    pub fn xy_idx(&self, x: i32, y: i32) -> usize {
+        (y as usize * self.width as usize) + x as usize
+    }
+
+    fn apply_room_to_map(&mut self, room : &Rect) {
+        for y in room.y1 +1 ..= room.y2 {
+            for x in room.x1 + 1 ..= room.x2 {
+                let idx = self.xy_idx(x, y);
+                self.tiles[idx] = TileType::Floor;
+            }
+        }
+    }
+
+    fn apply_horizontal_tunnel(&mut self, x1:i32, x2:i32, y:i32) {
+        for x in min(x1,x2) ..= max(x1,x2) {
+            let idx = self.xy_idx(x, y);
+            if idx > 0 && idx < self.width as usize * self.height as usize {
+                self.tiles[idx as usize] = TileType::Floor;
+            }
+        }
+    }
+
+    fn apply_vertical_tunnel(&mut self, y1:i32, y2:i32, x:i32) {
+        for y in min(y1,y2) ..= max(y1,y2) {
+            let idx = self.xy_idx(x, y);
+            if idx > 0 && idx < self.width as usize * self.height as usize {
+                self.tiles[idx as usize] = TileType::Floor;
+            }
+        }
+    }
+
+    fn is_exit_valid(&self, x:i32, y:i32) -> bool {
+        if x < 1 || x > self.width-1 || y < 1 || y > self.height-1 { return false; }
+        let idx = (y * self.width) + x;
+        !self.blocked[idx as usize]
+    }
+
+    pub fn populate_blocked(&mut self) {        
+        for (i,tile) in self.tiles.iter_mut().enumerate() {
+            self.blocked[i] = *tile == TileType::Wall;
+        }
+    }
+
+    pub fn clear_content_index(&mut self) {
+        for content in self.tile_content.iter_mut() {
+            content.clear();
+        }
+    }
+
+    /// Makes a new map using the algorithm from http://rogueliketutorials.com/tutorials/tcod/part-3/
+    /// This gives a handful of random rooms and corridors joining them together.
+    pub fn new_map_rooms_and_corridors() -> Map {
+        let mut map = Map{
+            tiles : vec![TileType::Wall; MAPCOUNT],
+            rooms : Vec::new(),
+            width : MAPWIDTH as i32,
+            height: MAPHEIGHT as i32,
+            revealed_tiles : vec![false; MAPCOUNT],
+            visible_tiles : vec![false; MAPCOUNT],
+            blocked : vec![false; MAPCOUNT],
+            tile_content : vec![Vec::new(); MAPCOUNT]
+        };
+
+        const MAX_ROOMS : i32 = 30;
+        const MIN_SIZE : i32 = 6;
+        const MAX_SIZE : i32 = 10;
+
+        let mut rng = RandomNumberGenerator::new();
+
+        for _i in 0..MAX_ROOMS {
+            let w = rng.range(MIN_SIZE, MAX_SIZE);
+            let h = rng.range(MIN_SIZE, MAX_SIZE);
+            let x = rng.roll_dice(1, map.width - w - 1) - 1;
+            let y = rng.roll_dice(1, map.height - h - 1) - 1;
+            let new_room = Rect::new(x, y, w, h);
+            let mut ok = true;
+            for other_room in map.rooms.iter() {
+                if new_room.intersect(other_room) { ok = false }
+            }
+            if ok {
+                map.apply_room_to_map(&new_room);
+
+                if !map.rooms.is_empty() {
+                    let (new_x, new_y) = new_room.center();
+                    let (prev_x, prev_y) = map.rooms[map.rooms.len()-1].center();
+                    if rng.range(0,1) == 1 {
+                        map.apply_horizontal_tunnel(prev_x, new_x, prev_y);
+                        map.apply_vertical_tunnel(prev_y, new_y, new_x);
+                    } else {
+                        map.apply_vertical_tunnel(prev_y, new_y, prev_x);
+                        map.apply_horizontal_tunnel(prev_x, new_x, new_y);
+                    }
+                }
+
+                map.rooms.push(new_room);
+            }
+        }
+
+        map
+    }
+}
+
+impl BaseMap for Map {
+    fn is_opaque(&self, idx:i32) -> bool {
+        self.tiles[idx as usize] == TileType::Wall
+    }
+
+    fn get_available_exits(&self, idx:i32) -> Vec<(i32, f32)> {
+        let mut exits : Vec<(i32, f32)> = Vec::new();
+        let x = idx % self.width;
+        let y = idx / self.width;
+
+        // Cardinal directions
+        if self.is_exit_valid(x-1, y) { exits.push((idx-1, 1.0)) };
+        if self.is_exit_valid(x+1, y) { exits.push((idx+1, 1.0)) };
+        if self.is_exit_valid(x, y-1) { exits.push((idx-self.width, 1.0)) };
+        if self.is_exit_valid(x, y+1) { exits.push((idx+self.width, 1.0)) };
+
+        // Diagonals
+        if self.is_exit_valid(x-1, y-1) { exits.push(((idx-self.width)-1, 1.45)); }
+        if self.is_exit_valid(x+1, y-1) { exits.push(((idx-self.width)+1, 1.45)); }
+        if self.is_exit_valid(x-1, y+1) { exits.push(((idx+self.width)-1, 1.45)); }
+        if self.is_exit_valid(x+1, y+1) { exits.push(((idx+self.width)+1, 1.45)); }
+
+        exits
+    }
+
+    fn get_pathing_distance(&self, idx1:i32, idx2:i32) -> f32 {
+        let p1 = Point::new(idx1 % self.width, idx1 / self.width);
+        let p2 = Point::new(idx2 % self.width, idx2 / self.width);
+        rltk::DistanceAlg::Pythagoras.distance2d(p1, p2)
+    }
+}
+
+impl Algorithm2D for Map {
+    fn point2d_to_index(&self, pt: Point) -> i32 {
+        (pt.y * self.width) + pt.x
+    }
+
+    fn index_to_point2d(&self, idx:i32) -> Point {
+        Point{ x: idx % self.width, y: idx / self.width }
+    }
+}
+
+pub fn draw_map(ecs: &World, ctx : &mut Rltk) {
+    let map = ecs.fetch::<Map>();
+
+    let mut y = 0;
+    let mut x = 0;
+    for (idx,tile) in map.tiles.iter().enumerate() {
+        // Render a tile depending upon the tile type
+
+        if map.revealed_tiles[idx] {
+            let glyph;
+            let mut fg;
+            match tile {
+                TileType::Floor => {
+                    glyph = rltk::to_cp437('.');
+                    fg = RGB::from_f32(0.0, 0.5, 0.5);
+                }
+                TileType::Wall => {
+                    glyph = rltk::to_cp437('#');
+                    fg = RGB::from_f32(0., 1.0, 0.);
+                }
+            }
+            if !map.visible_tiles[idx] { fg = fg.to_greyscale() }
+            ctx.set(x, y, fg, RGB::from_f32(0., 0., 0.), glyph);
+        }
+
+        // Move the coordinates
+        x += 1;
+        if x > MAPWIDTH as i32-1 {
+            x = 0;
+            y += 1;
+        }
+    }
+}

chapter-11-loadsave/src/map_indexing_system.rs

@@ -0,0 +1,32 @@
+extern crate specs;
+use specs::prelude::*;
+use super::{Map, Position, BlocksTile};
+
+pub struct MapIndexingSystem {}
+
+impl<'a> System<'a> for MapIndexingSystem {
+    type SystemData = ( WriteExpect<'a, Map>,
+                        ReadStorage<'a, Position>,
+                        ReadStorage<'a, BlocksTile>,
+                        Entities<'a>,);
+
+    fn run(&mut self, data : Self::SystemData) {
+        let (mut map, position, blockers, entities) = data;
+
+        map.populate_blocked();
+        map.clear_content_index();
+        for (entity, position) in (&entities, &position).join() {
+            let idx = map.xy_idx(position.x, position.y);
+
+            // If they block, update the blocking list
+            let _p : Option<&BlocksTile> = blockers.get(entity);
+            if let Some(_p) = _p {
+                map.blocked[idx] = true;
+            }
+            
+            // Push the entity to the appropriate index slot. It's a Copy
+            // type, so we don't need to clone it (we want to avoid moving it out of the ECS!)
+            map.tile_content[idx].push(entity);
+        }
+    }
+}

chapter-11-loadsave/src/melee_combat_system.rs

@@ -0,0 +1,40 @@
+extern crate specs;
+use specs::prelude::*;
+use super::{CombatStats, WantsToMelee, Name, SufferDamage, gamelog::GameLog};
+
+pub struct MeleeCombatSystem {}
+
+impl<'a> System<'a> for MeleeCombatSystem {
+    #[allow(clippy::type_complexity)]
+    type SystemData = ( Entities<'a>,
+                        WriteExpect<'a, GameLog>,
+                        WriteStorage<'a, WantsToMelee>,
+                        ReadStorage<'a, Name>,
+                        ReadStorage<'a, CombatStats>,
+                        WriteStorage<'a, SufferDamage>
+                      );
+
+    fn run(&mut self, data : Self::SystemData) {
+        let (entities, mut log, mut wants_melee, names, combat_stats, mut inflict_damage) = data;
+
+        for (_entity, wants_melee, name, stats) in (&entities, &wants_melee, &names, &combat_stats).join() {
+            if stats.hp > 0 {
+                let target_stats = combat_stats.get(wants_melee.target).unwrap();
+                if target_stats.hp > 0 {
+                    let target_name = names.get(wants_melee.target).unwrap();
+
+                    let damage = i32::max(0, stats.power - target_stats.defense);
+
+                    if damage == 0 {
+                        log.entries.insert(0, format!("{} is unable to hurt {}", &name.name, &target_name.name));
+                    } else {
+                        log.entries.insert(0, format!("{} hits {}, for {} hp.", &name.name, &target_name.name, damage));
+                        inflict_damage.insert(wants_melee.target, SufferDamage{ amount: damage }).expect("Unable to do damage");                        
+                    }
+                }
+            }
+        }
+
+        wants_melee.clear();
+    }
+}

chapter-11-loadsave/src/monster_ai_system.rs

@@ -0,0 +1,64 @@
+extern crate specs;
+use specs::prelude::*;
+use super::{Viewshed, Monster, Map, Position, WantsToMelee, RunState, Confusion};
+extern crate rltk;
+use rltk::{Point};
+
+pub struct MonsterAI {}
+
+impl<'a> System<'a> for MonsterAI {
+    #[allow(clippy::type_complexity)]
+    type SystemData = ( WriteExpect<'a, Map>,
+                        ReadExpect<'a, Point>,
+                        ReadExpect<'a, Entity>,
+                        ReadExpect<'a, RunState>,
+                        Entities<'a>,
+                        WriteStorage<'a, Viewshed>, 
+                        ReadStorage<'a, Monster>,
+                        WriteStorage<'a, Position>,
+                        WriteStorage<'a, WantsToMelee>,
+                        WriteStorage<'a, Confusion>);
+
+    fn run(&mut self, data : Self::SystemData) {
+        let (mut map, player_pos, player_entity, runstate, entities, mut viewshed, monster, mut position, mut wants_to_melee, mut confused) = data;
+
+        if *runstate != RunState::MonsterTurn { return; }
+
+        for (entity, mut viewshed,_monster,mut pos) in (&entities, &mut viewshed, &monster, &mut position).join() {
+            let mut can_act = true;
+
+            let is_confused = confused.get_mut(entity);
+            if let Some(i_am_confused) = is_confused {
+                i_am_confused.turns -= 1;
+                if i_am_confused.turns < 1 {
+                    confused.remove(entity);
+                }
+                can_act = false;
+            }
+
+            if can_act {
+                let distance = rltk::DistanceAlg::Pythagoras.distance2d(Point::new(pos.x, pos.y), *player_pos);
+                if distance < 1.5 {
+                    wants_to_melee.insert(entity, WantsToMelee{ target: *player_entity }).expect("Unable to insert attack");
+                }
+                else if viewshed.visible_tiles.contains(&*player_pos) {
+                    // Path to the player
+                    let path = rltk::a_star_search(
+                        map.xy_idx(pos.x, pos.y) as i32, 
+                        map.xy_idx(player_pos.x, player_pos.y) as i32, 
+                        &mut *map
+                    );
+                    if path.success && path.steps.len()>1 {
+                        let mut idx = map.xy_idx(pos.x, pos.y);
+                        map.blocked[idx] = false;
+                        pos.x = path.steps[1] % map.width;
+                        pos.y = path.steps[1] / map.width;
+                        idx = map.xy_idx(pos.x, pos.y);
+                        map.blocked[idx] = true;
+                        viewshed.dirty = true;
+                    }
+                }
+            }
+        }
+    }
+}

chapter-11-loadsave/src/player.rs

@@ -0,0 +1,115 @@
+extern crate rltk;
+use rltk::{VirtualKeyCode, Rltk, Point};
+extern crate specs;
+use specs::prelude::*;
+use super::{Position, Player, Viewshed, State, Map, RunState, CombatStats, WantsToMelee, Item,
+    gamelog::GameLog, WantsToPickupItem};
+
+pub fn try_move_player(delta_x: i32, delta_y: i32, ecs: &mut World) {
+    let mut positions = ecs.write_storage::<Position>();
+    let players = ecs.read_storage::<Player>();
+    let mut viewsheds = ecs.write_storage::<Viewshed>();
+    let entities = ecs.entities();
+    let combat_stats = ecs.read_storage::<CombatStats>();
+    let map = ecs.fetch::<Map>();
+    let mut wants_to_melee = ecs.write_storage::<WantsToMelee>();
+
+    for (entity, _player, pos, viewshed) in (&entities, &players, &mut positions, &mut viewsheds).join() {
+        let destination_idx = map.xy_idx(pos.x + delta_x, pos.y + delta_y);
+
+        for potential_target in map.tile_content[destination_idx].iter() {
+            let target = combat_stats.get(*potential_target);
+            if let Some(_target) = target {
+                wants_to_melee.insert(entity, WantsToMelee{ target: *potential_target }).expect("Add target failed");
+                return;
+            }
+        }
+
+        if !map.blocked[destination_idx] {
+            pos.x += delta_x;
+            pos.y += delta_y;
+
+            if pos.x < 0 { pos.x = 0; }
+            if pos.x > 79 { pos.y = 79; }
+            if pos.y < 0 { pos.y = 0; }
+            if pos.y > 49 { pos.y = 49; }
+
+            viewshed.dirty = true;
+            let mut ppos = ecs.write_resource::<Point>();
+            ppos.x = pos.x;
+            ppos.y = pos.y;
+        }
+    }
+}
+
+fn get_item(ecs: &mut World) {
+    let player_pos = ecs.fetch::<Point>();
+    let player_entity = ecs.fetch::<Entity>();
+    let entities = ecs.entities();
+    let items = ecs.read_storage::<Item>();
+    let positions = ecs.read_storage::<Position>();
+    let mut gamelog = ecs.fetch_mut::<GameLog>();    
+
+    let mut target_item : Option<Entity> = None;
+    for (item_entity, _item, position) in (&entities, &items, &positions).join() {
+        if position.x == player_pos.x && position.y == player_pos.y {
+            target_item = Some(item_entity);
+        }
+    }
+
+    match target_item {
+        None => gamelog.entries.insert(0, "There is nothing here to pick up.".to_string()),
+        Some(item) => {
+            let mut pickup = ecs.write_storage::<WantsToPickupItem>();
+            pickup.insert(*player_entity, WantsToPickupItem{ collected_by: *player_entity, item }).expect("Unable to insert want to pickup");
+        }
+    }
+}
+
+pub fn player_input(gs: &mut State, ctx: &mut Rltk) -> RunState {
+    // Player movement
+    match ctx.key {
+        None => { return RunState::AwaitingInput } // Nothing happened
+        Some(key) => match key {
+            VirtualKeyCode::Left => try_move_player(-1, 0, &mut gs.ecs),
+            VirtualKeyCode::Numpad4 => try_move_player(-1, 0, &mut gs.ecs),
+            VirtualKeyCode::H => try_move_player(-1, 0, &mut gs.ecs),
+
+            VirtualKeyCode::Right => try_move_player(1, 0, &mut gs.ecs),
+            VirtualKeyCode::Numpad6 => try_move_player(1, 0, &mut gs.ecs),            
+            VirtualKeyCode::L => try_move_player(1, 0, &mut gs.ecs),
+
+            VirtualKeyCode::Up => try_move_player(0, -1, &mut gs.ecs),
+            VirtualKeyCode::Numpad8 => try_move_player(0, -1, &mut gs.ecs),
+            VirtualKeyCode::K => try_move_player(0, -1, &mut gs.ecs),
+
+            VirtualKeyCode::Down => try_move_player(0, 1, &mut gs.ecs),
+            VirtualKeyCode::Numpad2 => try_move_player(0, 1, &mut gs.ecs),
+            VirtualKeyCode::J => try_move_player(0, 1, &mut gs.ecs),
+
+            // Diagonals
+            VirtualKeyCode::Numpad9 => try_move_player(1, -1, &mut gs.ecs),
+            VirtualKeyCode::Y => try_move_player(1, -1, &mut gs.ecs),
+
+            VirtualKeyCode::Numpad7 => try_move_player(-1, -1, &mut gs.ecs),
+            VirtualKeyCode::U => try_move_player(-1, -1, &mut gs.ecs),
+
+            VirtualKeyCode::Numpad3 => try_move_player(1, 1, &mut gs.ecs),
+            VirtualKeyCode::N => try_move_player(1, 1, &mut gs.ecs),
+
+            VirtualKeyCode::Numpad1 => try_move_player(-1, 1, &mut gs.ecs),
+            VirtualKeyCode::B => try_move_player(-1, 1, &mut gs.ecs),
+
+            // Picking up items
+            VirtualKeyCode::G => get_item(&mut gs.ecs),
+            VirtualKeyCode::I => return RunState::ShowInventory,
+            VirtualKeyCode::D => return RunState::ShowDropItem,
+
+            // Save and Quit
+            VirtualKeyCode::Escape => return RunState::SaveGame,
+
+            _ => { return RunState::AwaitingInput }
+        },
+    }
+    RunState::PlayerTurn
+}

chapter-11-loadsave/src/rect.rs

@@ -0,0 +1,21 @@
+pub struct Rect {
+    pub x1 : i32,
+    pub x2 : i32,
+    pub y1 : i32,
+    pub y2 : i32
+}
+
+impl Rect {
+    pub fn new(x:i32, y: i32, w:i32, h:i32) -> Rect {
+        Rect{x1:x, y1:y, x2:x+w, y2:y+h}
+    }
+
+    // Returns true if this overlaps with other
+    pub fn intersect(&self, other:&Rect) -> bool {
+        self.x1 <= other.x2 && self.x2 >= other.x1 && self.y1 <= other.y2 && self.y2 >= other.y1
+    }
+
+    pub fn center(&self) -> (i32, i32) {
+        ((self.x1 + self.x2)/2, (self.y1 + self.y2)/2)
+    }
+}

chapter-11-loadsave/src/spawner.rs

@@ -0,0 +1,194 @@
+extern crate rltk;
+use rltk::{ RGB, RandomNumberGenerator };
+extern crate specs;
+use specs::prelude::*;
+use super::{CombatStats, Player, Renderable, Name, Position, Viewshed, Monster, BlocksTile, Rect, Item, 
+    Consumable, Ranged, ProvidesHealing, map::MAPWIDTH, InflictsDamage, AreaOfEffect, Confusion};
+
+/// Spawns the player and returns his/her entity object.
+pub fn player(ecs : &mut World, player_x : i32, player_y : i32) -> Entity {
+    ecs
+        .create_entity()
+        .with(Position { x: player_x, y: player_y })
+        .with(Renderable {
+            glyph: rltk::to_cp437('@'),
+            fg: RGB::named(rltk::YELLOW),
+            bg: RGB::named(rltk::BLACK),
+            render_order: 0
+        })
+        .with(Player{})
+        .with(Viewshed{ visible_tiles : Vec::new(), range: 8, dirty: true })
+        .with(Name{name: "Player".to_string() })
+        .with(CombatStats{ max_hp: 30, hp: 30, defense: 2, power: 5 })
+        .build()
+}
+
+const MAX_MONSTERS : i32 = 4;
+const MAX_ITEMS : i32 = 2;
+
+/// Fills a room with stuff!
+pub fn spawn_room(ecs: &mut World, room : &Rect) {
+    let mut monster_spawn_points : Vec<usize> = Vec::new();
+    let mut item_spawn_points : Vec<usize> = Vec::new();
+
+    // Scope to keep the borrow checker happy
+    {
+        let mut rng = ecs.write_resource::<RandomNumberGenerator>();
+        let num_monsters = rng.roll_dice(1, MAX_MONSTERS + 2) - 3;
+        let num_items = rng.roll_dice(1, MAX_ITEMS + 2) - 3;
+
+        for _i in 0 .. num_monsters {
+            let mut added = false;
+            while !added {
+                let x = (room.x1 + rng.roll_dice(1, i32::abs(room.x2 - room.x1))) as usize;
+                let y = (room.y1 + rng.roll_dice(1, i32::abs(room.y2 - room.y1))) as usize;
+                let idx = (y * MAPWIDTH) + x;
+                if !monster_spawn_points.contains(&idx) {
+                    monster_spawn_points.push(idx);
+                    added = true;
+                }
+            }
+        }
+
+        for _i in 0 .. num_items {
+            let mut added = false;
+            while !added {
+                let x = (room.x1 + rng.roll_dice(1, i32::abs(room.x2 - room.x1))) as usize;
+                let y = (room.y1 + rng.roll_dice(1, i32::abs(room.y2 - room.y1))) as usize;
+                let idx = (y * MAPWIDTH) + x;
+                if !item_spawn_points.contains(&idx) {
+                    item_spawn_points.push(idx);
+                    added = true;
+                }
+            }
+        }
+    }
+
+    // Actually spawn the monsters
+    for idx in monster_spawn_points.iter() {
+        let x = *idx % MAPWIDTH;
+        let y = *idx / MAPWIDTH;
+        random_monster(ecs, x as i32, y as i32);
+    }
+
+    // Actually spawn the items
+    for idx in item_spawn_points.iter() {
+        let x = *idx % MAPWIDTH;
+        let y = *idx / MAPWIDTH;
+        random_item(ecs, x as i32, y as i32);
+    }
+}
+
+fn random_monster(ecs: &mut World, x: i32, y: i32) {
+    let roll :i32;
+    {
+        let mut rng = ecs.write_resource::<RandomNumberGenerator>();
+        roll = rng.roll_dice(1, 2);
+    }
+    match roll {
+        1 => { orc(ecs, x, y) }
+        _ => { goblin(ecs, x, y) }
+    }
+}
+
+fn random_item(ecs: &mut World, x: i32, y: i32) {
+    let roll :i32;
+    {
+        let mut rng = ecs.write_resource::<RandomNumberGenerator>();
+        roll = rng.roll_dice(1, 4);
+    }
+    match roll {
+        1 => { health_potion(ecs, x, y) }
+        2 => { fireball_scroll(ecs, x, y) }
+        3 => { confusion_scroll(ecs, x, y) }
+        _ => { magic_missile_scroll(ecs, x, y) }
+    }
+}
+
+fn orc(ecs: &mut World, x: i32, y: i32) { monster(ecs, x, y, rltk::to_cp437('o'), "Orc"); }
+fn goblin(ecs: &mut World, x: i32, y: i32) { monster(ecs, x, y, rltk::to_cp437('g'), "Goblin"); }
+
+fn monster<S : ToString>(ecs: &mut World, x: i32, y: i32, glyph : u8, name : S) {
+    ecs.create_entity()
+        .with(Position{ x, y })
+        .with(Renderable{
+            glyph,
+            fg: RGB::named(rltk::RED),
+            bg: RGB::named(rltk::BLACK),
+            render_order: 1
+        })
+        .with(Viewshed{ visible_tiles : Vec::new(), range: 8, dirty: true })
+        .with(Monster{})
+        .with(Name{ name : name.to_string() })
+        .with(BlocksTile{})
+        .with(CombatStats{ max_hp: 16, hp: 16, defense: 1, power: 4 })
+        .build();
+}
+
+fn health_potion(ecs: &mut World, x: i32, y: i32) {
+    ecs.create_entity()
+        .with(Position{ x, y })
+        .with(Renderable{
+            glyph: rltk::to_cp437('¡'),
+            fg: RGB::named(rltk::MAGENTA),
+            bg: RGB::named(rltk::BLACK),
+            render_order: 2
+        })
+        .with(Name{ name : "Health Potion".to_string() })
+        .with(Item{})
+        .with(Consumable{})
+        .with(ProvidesHealing{ heal_amount: 8 })
+        .build();
+}
+
+fn magic_missile_scroll(ecs: &mut World, x: i32, y: i32) {
+    ecs.create_entity()
+        .with(Position{ x, y })
+        .with(Renderable{
+            glyph: rltk::to_cp437(')'),
+            fg: RGB::named(rltk::CYAN),
+            bg: RGB::named(rltk::BLACK),
+            render_order: 2
+        })
+        .with(Name{ name : "Magic Missile Scroll".to_string() })
+        .with(Item{})
+        .with(Consumable{})
+        .with(Ranged{ range: 6 })
+        .with(InflictsDamage{ damage: 20 })
+        .build();
+}
+
+fn fireball_scroll(ecs: &mut World, x: i32, y: i32) {
+    ecs.create_entity()
+        .with(Position{ x, y })
+        .with(Renderable{
+            glyph: rltk::to_cp437(')'),
+            fg: RGB::named(rltk::ORANGE),
+            bg: RGB::named(rltk::BLACK),
+            render_order: 2
+        })
+        .with(Name{ name : "Fireball Scroll".to_string() })
+        .with(Item{})
+        .with(Consumable{})
+        .with(Ranged{ range: 6 })
+        .with(InflictsDamage{ damage: 20 })
+        .with(AreaOfEffect{ radius: 3 })
+        .build();
+}
+
+fn confusion_scroll(ecs: &mut World, x: i32, y: i32) {
+    ecs.create_entity()
+        .with(Position{ x, y })
+        .with(Renderable{
+            glyph: rltk::to_cp437(')'),
+            fg: RGB::named(rltk::PINK),
+            bg: RGB::named(rltk::BLACK),
+            render_order: 2
+        })
+        .with(Name{ name : "Confusion Scroll".to_string() })
+        .with(Item{})
+        .with(Consumable{})
+        .with(Ranged{ range: 6 })
+        .with(Confusion{ turns: 4 })
+        .build();
+}

chapter-11-loadsave/src/visibility_system.rs

@@ -0,0 +1,37 @@
+extern crate specs;
+use specs::prelude::*;
+use super::{Viewshed, Position, Map, Player};
+extern crate rltk;
+use rltk::{field_of_view, Point};
+
+pub struct VisibilitySystem {}
+
+impl<'a> System<'a> for VisibilitySystem {
+    type SystemData = ( WriteExpect<'a, Map>,
+                        Entities<'a>,
+                        WriteStorage<'a, Viewshed>, 
+                        ReadStorage<'a, Position>,
+                        ReadStorage<'a, Player>);
+
+    fn run(&mut self, data : Self::SystemData) {
+        let (mut map, entities, mut viewshed, pos, player) = data;
+
+        for (ent,viewshed,pos) in (&entities, &mut viewshed, &pos).join() {
+            if viewshed.dirty {
+                viewshed.dirty = false;
+                viewshed.visible_tiles = field_of_view(Point::new(pos.x, pos.y), viewshed.range, &*map);
+
+                // If this is the player, reveal what they can see
+                let _p : Option<&Player> = player.get(ent);
+                if let Some(_p) = _p {
+                    for t in map.visible_tiles.iter_mut() { *t = false };
+                    for vis in viewshed.visible_tiles.iter() {
+                        let idx = map.xy_idx(vis.x, vis.y);
+                        map.revealed_tiles[idx] = true;
+                        map.visible_tiles[idx] = true;
+                    }
+                }
+            }
+        }
+    }
+}